The present application relates to a laser processing apparatus and a laser processing method for performing pattern processing on a transparent conductive film that is used for a transparent electrode on a multilayer thin film of a FPD (Flat Panel Display) and the like. Particularly, the present application relates to a laser processing apparatus and laser processing method as well as a debris extraction mechanism and an debris extraction method for removing and extracting debris that is particles and products generated during laser processing based on ablation, thermofusion or composite action thereof in which a surface of a processing object is irradiated with laser light.
A transparent conductive film is used as a transparent electrode of a multilayer film substrate for a flat display panel, of a solar cell and the like. Also a transparent conductive film is widely used as a transparent electrode in the field of electronic paper whose development has been promoted as a future display device, and the use thereof has been expanded. Further, since competition for higher definition and lower costs of a display has become more intensive recently, a transparent conductive film of higher quality and higher productivity may also be required in manufacturing a display.
Such transparent conductive film is typically patterned into a desired shape by a photolithography method. For example, a transparent conductive film made of an ITO (Indium Tin Oxides) film, a ZnO (Zinc Oxides) film or the like is vacuum-coated on a glass, plastic, or silicon wafer substrate or the like, then a resist layer is formed thereon, and the resist layer is exposed by irradiation of light through a photomask having a predetermined pattern. The photomask pattern is transcribed onto the resist layer by performing development and post bake, then a portion of the transparent conductive film not covered with the resist is removed by wet etching, and the remaining resist layer is removed at the end so that the desired pattern of the transparent conductive film is obtained.
However, the photolithography process described above needs a large scale apparatus such as a coater/developer, which causes a problem in view of a facility investment and footprint. In addition, since a large amount of chemical solution such as developing solution is used, there is also caused a problem in view of environmental preservation. Japanese Published Patent Application No. 2004-153171 discloses technology for directly processing a transparent conductive film by using laser light, with which a manufacturing process is simplified by omitting additional photolithography processing.
In the processing using a laser which is disclosed in Japanese Published Patent Application No. 2004-153171, particles and products generated from a surface of a processing object irradiated by the laser light may re-deposit around a processed region. Those products are typically called debris. If such debris re-deposits on a substrate, there is a possibility that desired processing quality and processing accuracy may not be obtained. Certain methods are known for reducing debris, for example:
(i) A method of controlling generation of debris;
(ii) A method of removing debris after the debris deposits on a substrate;
(iii) A method of reducing deposition of debris.
In order to reduce the generation of debris in the above method (i), it is known that blowing an assist gas together with the irradiation of laser light onto a processing object is effective. Japanese Published Patent Application No. 09-192870 discloses a method (hereinafter, referred to as method 1), in which an inner side nozzle is disposed in a laser processing head and an outer side nozzle is disposed to surround an outer circumferential surface thereof. In this method 1, an assist gas is directed toward a processed region from the inner side nozzle, and debris is extracted by sucking the assist gas using the outer side nozzle. Further, a method of decomposing debris or preventing re-deposition thereof by using a predetermined atmospheric gas is known as a method of controlling generation of debris and also it is known that an amount of debris deposited on the processed object can be greatly reduced by performing the laser processing under reduced pressure conditions of about 10 [Pa] (10-2 Torr).
Further, as the method of removing debris after the deposition on the processing object in the above item (ii), Japanese Published Patent Application No. 2004-337947 discloses a laser processing method (hereinafter, referred to as method 2) of sucking debris generated near the processing object together with an assist gas. In this method 2, there is provided a laser processing head for outputting laser light toward the processing object with a nozzle mounted on the side facing the processing object. The processing object is irradiated by the laser light output from the laser processing head together with the assist gas through a gas inlet path of the nozzle, and debris generated near the processing object is sucked together with the assist gas from a circular gas suction hole provided on an outer circumference side of the gas inlet path of the nozzle.
Further, Japanese Published Patent Application No. 10-99978 discloses a method (hereinafter, referred to as method 3) of reducing deposition of debris as described in the above item (iii). In this method 3, a fluid feed apparatus is provided for directing gas onto a surface in the vicinity of a processed region and debris is blown away from the processed region by a suction duct for sucking the fluid provided on the opposite side, and therefore gas is directed and is simultaneously sucked to remove the debris.
A configuration disclosed in the above-described Japanese Published Patent Application No. 10-99978 is explained by referring to FIG. 1. The apparatus shown in FIG. 1 is a laser processing apparatus for stamping a manufacturer's serial number on a glass substrate 4 which is arranged in part of a manufacturing process for manufacturing a predetermined product. Various coating processing and patterning are performed on the glass substrate 4 through a series of manufacturing processes by using a plurality of processing machines. This laser processing apparatus includes: a processing table 7, a laser irradiation apparatus 2, a fluid feed apparatus 11, and a discharge apparatus 10. The processing table 7 determines the position of a stamp region where the manufacturer's serial number is stamped by moving in two directions parallel with a plane of the mounted glass substrate 4. The laser irradiation apparatus 2 stamps the manufacturer's serial number corresponding to the kind of the mounted glass substrate 4 onto a stamp region 8. The fluid feed apparatus 11 has a blow nozzle 12 for directing a fluid to the stamp region 8 of the glass substrate 4 mounted on the processing table 7. The discharge apparatus 10 has a suction duct 9 for sucking the fluid over the stamp region 8. Debris 13 generated by irradiation of laser light 3 on a black matrix 6 of the stamp region 8 is removed when processing the glass substrate 4 by the laser light 3 that is emitted from a laser control apparatus 1 through an objective lens 5 of the laser irradiation apparatus 2.
However, debris is scattered and deposits again even if an assist gas is blown onto the processed region from the inner side nozzle as described in the method 1, and therefore debris may not be removed sufficiently even if suction power of the outer side nozzle is made strong. In addition, even if an atmospheric fluid is sucked by the circular gas suction hole as described in the method 2, there has been such a problem that debris that scatters in every direction may not be extracted completely. Similarly, even if debris is blown away from the surface in the vicinity of the processed region in order to suck and remove debris as described in the method 3, debris may not be sucked completely and therefore a result becomes the same as that the remaining debris is scattered along the flow. In this regard, it has been difficult to remove and extract debris even if the suction power is increased.
It is therefore desirable to efficiently remove debris generated from a processing object when pattern processing is performed by irradiating the object with laser light and to reduce the debris re-deposited on a processing object.